A large simple clinical trial prototype for assessment of OTC drug effects using patient-reported data

Abstract

Purpose: Innovative methods are needed to assess risks related to treatment for common medical conditions, where therapy is usually patient-directed or over-the-counter (OTC), and where tolerability, i.e. patient experienced events, may affect patterns of use. A large-scale, blinded, randomised trial was conducted to compare the tolerability of paracetamol (acetaminophen), aspirin and ibuprofen at OTC doses, with patient-reported adverse event (AE) data as the primary outcome.

Methods: Patients with mild to moderate pain were randomised to either: paracetamol up to 3 g/d, aspirin up to 3 g/d or ibuprofen up to 1200 mg/d for 7 days. Patients recorded AE and severity in a diary as the primary data source. After inclusion, contact with patients by general practitioner (GP) investigators was by telephone after 24 hours and 7-9 days, and unscheduled visits, when GPs recorded AE. The study outcome was the frequency of significant adverse event (SGAE) (serious, severe, moderate or undefined intensity, or resulting in withdrawal or an investigator visit).

Results: Of 8677 patients included, 44 patients were non-evaluable, leaving 8633 evaluable patients; 1347 patients reported SGAE (paracetamol: 14.5%, aspirin: 18.7%, ibuprofen: 13.7%). Completed diaries were returned by 98.5% of patients, and only 49 cases were lost to follow-up (0.6%). Almost all patients were contacted by telephone, 99.3% at the first call, and 98.5% at the second. Most SGAE were reported by patients; only 27 patients (2%) had a SGAE reported only by the GP. The tolerability rankings by treatment were consistent for all categories of SGAE: aspirin had the highest incidence of SGAE, and ibuprofen and paracetamol, lower, comparable incidences.

Conclusions: A large, simple, randomised trial with patient-generated data can provide a sensitive source of information on AE, particularly in comparative safety assessments of OTC medications and other short-term therapies. This suggests reconsideration of the view that investigators are the most valid source for identifying and reporting AE.